Outdoor waste gas, such as landfill gas, can present problems such as foul odor and environmental pollution. Landfill gas is organic waste generated as a landfill decomposes. Typically, this foul-smelling gas consists of fifty-five percent methane, forty-four percent carbon dioxide, and one percent various other constituents, ranging from hydrogen sulfide to complex hydrocarbons. Undesirably, landfill gas may cause severe odor problems when released directly into the atmosphere. Further, methane has been characterized as a "greenhouse" gas, which is believed to significantly contribute to global warming.
Once landfills have reached full capacity, they are generally capped with, among other things, a layer of topsoil to support vegetation and help prevent erosion. A gas vent, gas well, or other gas collection system is typically provided in order to enable the landfill gas generated by the decomposition process to conveniently pass through the cap for release (e.g., in a passive arrangement).
Because landfill gas burns relatively cleanly, the gas emerging from such a vent, etc., may be burned in an effort to eliminate the noxious odor and harmful greenhouse effects. One possibility is to provide a flare to burn the gas as it emerges from the vent. However, disadvantages may result; for instance, it may be difficult to ensure that a flame burns continuously once the flare has been ignited. Several factors may contribute to this difficulty, including variations in the flow rate of the gas as a result of environmental conditions such as temperature and ground water levels. Furthermore, gas flows are commonly subject to variability due to barometric pressure and gas quality changes. Variations in percentage composition of the constituents (e.g., methane and carbon dioxide) of the landfill gas may also alter the gas/air mixture from an optimal ratio suited for maintaining or preserving a continuous flame. Moreover, adverse weather conditions such as wind and/or precipitation (e.g., snow, ice, sleet, hail and/or rain) may tend to extinguish the flame.
Preferably, a flare would be situated near the landfill, to minimize lengths of gas pipes needed. Usually, the flare would be disposed in a remote location, where it would be difficult to monitor the presence of flame, and inconvenient to manually reignite the flare in the event the flame is extinguished. During any time in which the flame is out, gas would disadvantageously be released into the atmosphere, thereby presenting the problem of potentially lengthy periods in which odor and greenhouse effects of the landfill would not be treated.
Various devices may be tried in attempts to address such problems. For instance, vent flares may be provided with electronic ignitors or propane pilot lights. Generally, electronic ignitors include sophisticated technology to monitor the presence of a flame. For example, optical or heat sensors may be employed which activate electronic circuitry upon detecting absence of a flame. A shortcoming of such sophisticated equipment is the relatively large expense in terms of up-front capital expenditure and routine maintenance.
Another approach may employ propane pilot light systems to help ensure that the landfill gas flame burns continuously, by providing a continuously burning pilot light. This type of system has the advantage of being relatively unsophisticated and thus, relatively inexpensive to purchase and simple to maintain. However, a drawback of this approach is that the system requires a separate supply of fuel (i.e., propane) which must be replaced periodically. In addition, the pilot light itself may be extinguished by, for example, wind and/or precipitation, undesirably requiring manual re-lighting.
As an improvement over such previous attempts, an exemplary configuration for a landfill gas vent flare is disclosed in U.S. application Ser. No. 08/559,795 by Hansen (entitled "Self Ignited Landfill Gas Vent Flare and Flarehead," filed Nov. 15, 1995, and assigned to Hansen Family Limited Partnership), which is hereby incorporated herein by reference in its entirety. In one aspect, such a landfill gas vent flare comprises a flarehead and at least one spark initiator. The flarehead is adapted for communication with a landfill gas vent, wherein landfill gas is permitted to flow in a downstream direction from the landfill gas vent to the flarehead. The at least one spark initiator is disposed on the flarehead, and is adapted to generate a continuous series of sparks in the flarehead, wherein the landfill gas flowing in the flarehead is ignited and continuously burned.
However, it remains desirable to provide refinements to the sparking in such a flarehead, for example, through special characteristics which enhance re-ignition over a variety of operating conditions. For instance, should a conventional spark plug be employed, water or ice may short-circuit the plug, or cold weather may shatter the insulation of the plug.
Thus, a need exists for a configuration which advantageously prevents or lessens short-circuiting of a sparking device, such as when snow, ice, sleet, hail and/or rain wets the, for example, hot and/or ground electrodes. A further need exists for formation or shaping of, for instance, the hot and/or ground electrodes, and/or formation or positioning of insulation therebetween, to enhance robustness, dependability, reliability, stability, resiliency and/or durability of such a sparking device. Another need exists for such a sparking device which is economical and/or suited for application(s) such as outdoor waste gas vent flares (e.g., passive landfill gas vent flares).